He has been charged with money laundering and deception, but police say their investigation is continuing. His relationship with the gang who tried to break into the network is unknown.

They have issued a warning for banks and businesses to watch out for cyber criminals.

The National Hi-Tech Crime Unit was launched in April 2001 with responsibility for tracking down the growing range of criminals who operate in cyberspace.

Takashi Morita, head of communications at Sumitomo Mitsui in Tokyo, said the company had not suffered any financial loss as a consequence of the robbery attempt.

He said: "The case is still in the middle of investigation so we cannot comment further.

"We have undertaken various measures in terms of security and we have not suffered any financial damage."

This will be discussed by chief executives and others for some time to come and it will further reinforce the need for corporate asset protection systems

Richard StarnesComputer security expert

Richard Starnes, president of the Information Security Services Association, said: "We have been talking about the doomsday scenario for quite some time and while this was not actualised it shows the magnitude of the threat to companies."

He told the BBC News Website: "This will be discussed by chief executives and others for some time to come and it will further reinforce the need for corporate asset protection systems."

Mr Starnes, who works for Cable & Wireless, said key logging software - which detects every key stroke made by a keyboard and can give away crucial information such as passwords - was easy to obtain and quite simple to insert into a company's computers.

He said: "This is the arms race of this era. Police and criminals are constantly trying to stay one step ahead of each other."